Calendar: remove past events.

wiki/src/contribute/calendar.mdwn

@@ -4,13 +4,6 @@ All times are referenced to Berlin and Paris time.
 
 ## 2018Q3
 
-* 2018-08-08 to 2018-08-09: port Tails to Tor Browser based on Firefox
-  60ESR ([[!tails_ticket 15023]]) — intrigeri and segfault
-
-* 2018-08-15: Feature freeze for 3.9. Everything you want to see in
-  Tails 3.9 must be merged into our devel branch by 17:00 CEST
-  that day.
-
 * 2018-08-16: Build and upload tentative 3.9~rc1 ISO image — intrigeri
 
 * 2018-08-17: Test and release 3.9~rc1 — intrigeri